This invention relates to a process of treating a gasification residue that is formed by the gasification of sulfur-containing granular fuels at temperatures from 700.degree. to 1100.degree. C. in a fluidized bed reactor, which in addition to the fuels and an oxygen-containing fluidizing gas is supplied with at least one alkaline earth metal carbonate or alkaline earth metal oxide for effecting an at least partial desulfurization of the product gas formed by the gasification, wherein the gasification residue withdrawn from the gasifier contains 8 to 80% by weight coke, 2 to 45% by weight alkaline earth metal sulfide, and 1 to 25% by weight alkaline earth metal oxide. The alkaline earth metals usually consist of Ca and/or Mg.